Chemical analysis and calcium channel blocking activity of the essential oil of perovskia abrotanoides

The aim of this study was to investigate the chemical composition and provide a pharmacological base for the medicinal use of the essential oil of Perovskia abrotanoides (Pa.Oil) in gastrointestinal disorders, such as colic. The chemical investigation resulted in the identification of 26 compounds, of which tricyclene, β-trans-ocimene, terpinene-4-acetate, terpinen-4-ol, caran-3β-ol, linalyl acetate, β-caryophyllene oxide and α-elemene had not previously been reported from P. abrotanoides. Major constituents were 1,8-cineol and δ-3-carene, which constituting 50% of the oil. In the isolated rabbit jejunum preparation Pa.Oil caused inhibition of spontaneous and high K⁺ (80 mM)-induced contractions, with respective EC⁵⁰ values of 0.13 (0.08-0.20; n=4) and 0.90 mg/mL (0.50-1.60; n=5), thus showing that spasmolytic activity is mediated possibly through calcium channel blockade (CCB). The CCB activity was confirmed when pre-treatment of the tissue with Pa.Oil (0.03-0.1 mg/mL) caused a rightward shift in the Ca⁺⁺ concentration-response curves, similar to that caused by verapamil, a standard calcium channel blocker. These data indicate that the essential oil of P. abrotanoides possesses spasmolytic activity mediated possibly through inhibition of voltage-dependent calcium channels, which may explain its medicinal use in colic and possibly diarrhea.